Digital X-ray detectors have electronic sensors of X-ray electromagnetic energy. The digital X-ray detectors are often referred to as solid-state X-ray detectors.
One type of conventional digital X-ray detector includes an array of pixels composed of switches as FETs (field effect transistors) and light detectors such as photodiodes, the pixels being constructed of amorphous silicon, over which Cesium Iodide (CsI) is deposited. CsI absorbs the X-rays and converts them to light, which is then detected by the photodiodes. The photodiode acts as a capacitor and will store charge. Initialization of the detector takes place prior to an X-ray exposure, when during the course of “scrubbing” the detector, each photodiode is charged to a known voltage. The detector is then exposed to X-rays which are absorbed by the CsI. Light that is emitted in proportion to the X-ray flux then partially discharges the photodiode. After the conclusion of the exposure, the voltage on the photodiode is restored to the initial voltage. The amount of charge required to restore the initial voltage on the photodiode is measured, which becomes a measure of the X-ray dose integrated by the pixel during the length of the exposure. The pixel array is arrayed in a flat panel.
A motherboard includes readout electronics that control readout of the electrical charge from the panel. The primary source of heat in the digital X-ray detectors is the motherboard. Heat is damaging to all electronic equipment, including the panel, and therefore, dissipation of the heat is an important goal in the design of digital X-ray detectors. In addition, U.S. Food and Drug Administration (FDA) safety regulations limit the temperature of the surfaces of medical devices (including digital X-ray detectors) intended for patient contact. Conventional thermal cooling methods in X-ray detectors have been limited to liquid based recirculating heat-exchangers. The conventional cooling methods have been shown to be overly cumbersome, fraught with technical difficulties given the incompatibility of liquids and electronics, as well as expensive. Thus, less expensive and less cumbersome techniques of cooling patient surfaces of digital X-ray detectors would be beneficial.
Furthermore, conventional digital X-ray detectors perform detector diagnostic tests during initial calibration or during service maintenance activities. Additional diagnostic testing during idle periods of the digital X-ray detectors may ensure that the digital X-ray detector is available for use and is functioning properly.